Combined oven and fume incinerator and method of operating same

Abstract

A combined oven and fume incinerator having an enclosed housing. A combustion chamber serving as a heat source and fume incinerator is connected by a heat recovery air duct to a process zone which in turn opens into a cool air inlet passage leading to the combustion chamber and blower means are provided to circulate air through the housing, combustion chamber, heat recovery duct, process zone, cool air inlet passage and back to the combustion chamber. The heat recovery duct is in direct thermal contact with the cool air inlet passage. An exhaust fan is located in the cool air inlet passage at a point where there is the least pollution to exhaust a portion of the air in the passage to atmosphere.

I claim: 
     
       1. A combined oven and fume incinerator for treating a product comprising an enclosed housing having a top wall and front and rear walls, means for moving said product through said housing, a plurality of process zones in said housing for treating said product, a combustion chamber forming a fume incinerator and a source of heat for said oven, fresh air inlet means extending into said housing, a hot air outlet duct extending from said combustion chamber to said process zones, a cool air inlet passage in said housing formed in part by said top wall, said front and rear walls and said hot air outlet duct and extending to said combustion chamber, blower means for circulating air within said housing through said process zones into said air inlet passage, a combustion chamber, hot air outlet and back to said process zones, and an exhaust fan for exhausting a part of the air from said cool air inlet at a position where said air is least contaminated with fume to the exterior of the housing with the air not exhausted being recycled through said combustion chamber by said blower means. 
     
     
       2. A combined oven and fume incinerator for treating a product comprising an enclosed housing having a product exiting end wall at one end of said housing through which a product enters the housing, a product exit end wall at an opposite end of the housing through which a product exits the housing, a top wall, front and rear walls, means for moving a product through the housing, at least one product process zone in said housing for treatment of a product, a combustion chamber in said housing adjacent one end wall forming a fume incinerator and to provide a source of heat for said oven, a heat recovery duct within the housing extending from said combustion chamber adjacent said one end wall towards the other end wall to each process zone, a cool air inlet passage within said housing formed in part by said top wall, said front and rear walls, and said heat recovery duct in direct thermal contact with said heat recovery duct whereby cool air in said inlet passage is preheated by hot air in said heat recovery duct prior to entry to said combustion chamber, blower means for circulating air within said housing through said cool air inlet passage, combustion chamber,heat recovery duct and each said process zone, and an exhaust fan positioned near said other end wall for exhausting a portion of the air from the cool air inlet passage with substantially the remainder of the air in said passage being recycled to said combustion chamber. 
     
     
       3. A combined oven and fume incinerator according to claim 2 wherein make up air enters into said housing through a product entry slot in said product entry wall and through a product exit slot in said product exit wall. 
     
     
       4. A combined oven and fume incinerator according to claim 2 having in addition a perforated drum in each process zone over which the product is adapted to pass, a blower means associated with each drum, and a distribution passage associated with each drum extending from said heat recovery duct to the inlet of each said blower means with the outlet of each said blower means communicating with the exterior of a drum whereby air flows through a drum into a process zone. 
     
     
       5. A combined oven and fume incinerator according to claim 4 having a plurality of process zones. 
     
     
       6. A combined oven and fume incinerator according to claim 5 wherein said combustion chamber is adjacent said product exit wall and said exhaust fan is positioned near the product entry wall. 
     
     
       7. A combined oven and fume incinerator according to claim 6 having in addition damper means in each said distribution passage for regulating flow of heated air into each process zone. 
     
     
       8. A combined oven and fume incinerator according to claim 5 or 6 having in addition adjustable vent means in said heat recovery duct for controllably returning hot air from said duct to said inlet passage. 
     
     
       9. A combined oven and fume incinerator according to claim 2 having in addition a combustion blower means associated with said combustion chamber for blowing the recycled air from said inlet passage into said combustion chamber. 
     
     
       10. A method of operating a combined oven and fume incinerator to treat a product having an enclosed housing, a combustion chamber forming a fume incinerator and a source of heat for said oven, a plurality of process zones in said housing, a cool air inlet passage extending from said process zones to said combustion chamber, a hot air duct extending from said combustion chamber to said process zones, a blower means for circulating air in said housing through said combustion chamber into said hot air duct to said process zones and from said process zones to said air inlet passage and from said air inlet passage into said combustion chamber, and an exhaust fan for exhausting a portion of the air from said cool air inlet passage; comprising the steps of simultaneously exhausting a portion of the air circulating in said cool air inlet which is least contaminated with fume to a point exterior of the housing and recycling the remaining air in said cool air inlet passage through said combustion chamber.